The present invention relates generally to a multilayer acoustical and thermal liner/insulator which may be utilized to insulate an environment such as a passenger compartment of a vehicle from the heat and sound generated by mechanical components of that vehicle during its operation. Further uses include application in insulating appliances such as dishwashers and clothes dryers and providing sound and thermal insulation for furnaces, air conditioning units and ductwork in buildings including homes, offices and industrial structures.
Acoustical insulation is well known in the art. Acoustical insulation typically relies upon both sound absorption, i.e. the ability to absorb incident sound waves, and transmission loss, i.e. the ability to reflect incident sound waves, in order to provide sound attenuation. One of the more prevalent uses of such insulation is in the motorized vehicle field where engine compartments, fire walls, fender wells, doors, floor pans and other components of the passenger compartment shell are commonly acoustically insulated to reduce engine and road noise for the benefit and comfort of passengers.
Mats of high temperature glass fibers have also been utilized, e.g. (a) on the fire wall between the dashboard and engine compartment and (b) along the floor pan of the vehicle between the passenger compartment and the drive line and exhaust system. These materials provide heat insulation which makes it possible to maintain cooler and more comfortable temperatures in the operator/passenger compartment particularly during the summer months. Additionally, these materials provide needed sound insulation, reducing or eliminating various mechanical sounds of the motor, drive train as well as the suspension and tires as the vehicle travels over the often rough and bumpy surface of the roadway.
Various methods of manufacturing or fabricating such acoustical and thermal insulators are known in the art. Examples of these methods are found, for example, in U.S. Pat. No. 5,055,341 to Yamaji et al. and U.S. Pat. No. 5,501,898 to Fottinger et al.
In the Yamaji et al. patent, woven and/or non-woven fabrics are laminated to a composite of fibers and thermal plastic resin. In the Fottinger et al. patent, a multilayer, multi-density composite is disclosed incorporating polyester fibers. The fibers are preheated in a furnace by metal plates above the melting point of the fibers. The non-woven fabric fiber layers are loaded into a molding tool and exposed to molding pressure for a dwell time sufficient to complete the molding process. The part is then cooled below the softening temperature of the fibers to set the composite in the final molded shape.
Various additional examples of acoustical insulation commonly employed for vehicle applications are found in U.S. Pat. Nos. 5,298,694 to Thompson et al., 5,624,726 to Sanocki et al., 5,759,659 to Sanocki et al. and 5,961,904 to Swan et al.
The Thompson et al. patent discloses a non-woven acoustical insulation web of thermoplastic fibers and a second layer, such as a scrim, non-woven fabric, film or foil, laminated thereto for water barrier protection.
The Sanochi et al. patents disclose an acoustical insulation blanket in the form of a composite featuring an insulation layer of fibrous insulation, foam insulation or a combination thereof and a high temperature-resistant layer of ceramic paper, woven ceramic fibers, woven fiberglass fibers, ceramic non-woven scrims or fiberglass non-woven scrims encased in a heat sealable thermoplastic polyolefin which functions as a moisture barrier.
The Swan et al patent discloses a non-woven acoustical insulation web of thermally stabilizing melt-blown polypropylene microfibers which may also contain staple fibers such as crimped bulking fibers and/or binder fibers. The acoustical insulation web is formed as a laminate with a water barrier layer of planer thermoplastic polyolefin film such as polyethylene, polypropylene and ethylene-propylene copolymer films.
In other instances, manufacturers have utilized one or more layers of ethylene vinyl acetate and/or polyvinyl chloride to provide the desired moisture barrier. The added water barrier layer(s) often add significant weight to the insulation product. This is a very significant disadvantage to vehicle manufacturers seeking to reduce overall vehicle weight and increase fuel economy.
In many acoustical insulation applications and particularly those relating to motorized vehicles, water barrier protection is a critical concern. As demonstrated by these prior art patents, it has generally been found necessary to add water barrier protection to the acoustical insulation material since this material is otherwise too pervious to water and allows water intrusion. Toward this end it has been common practice to provide laminate constructions which are effective for the intended purpose but suffer several shortcomings. Specifically, as a result of handling and manipulation during installation and/or deleterious and degradating effects of various environmental factors over time, delamination commonly occurs. This delamination typically reduces the effectiveness of the water barrier thereby potentially allowing for unwanted water intrusion by wicking and capillary action. A need is therefore identified for an improved insulation providing enhanced acoustical and thermal insulating properties and dependable water barrier protection over an extended service life all in a light weight product suitable for use even in compact and subcompact vehicles.
In accordance with the purposes of the present invention as described herein, an improved acoustical and thermal liner/insulator of enhanced performance characteristics is provided. The liner/insulator includes a pad of fibrous material having a lofty, acoustically insulating portion having a density of between substantially 8.0-80.0 kg/m3. The liner/insulator also includes a relatively higher density skin along at least one face thereof. The skin has a thickness of between substantially 0.25-10.0 mm and a density of between substantially 32.0-1600.0 kg/m3.
The fibrous material of the liner/insulator is selected from a group consisting of (a) thermoplastic polymer staple fibers and thermoplastic bicomponent fibers,(b) glass staple fibers and thermoplastic bicomponent fibers and (c) a combination of (a) and (b). The fibrous material may be polyester, polyethylene, polypropylene, polyethylene terephthalate, glass fibers, natural fibers and any mixtures thereof.
The pad is a nonlaminate and, accordingly, the potential for the relatively higher density skin to delaminate from the remainder of the pad is eliminated. In one embodiment of the invention, the pad includes a higher density skin along a second face thereof as well. In yet another embodiment, the liner/insulator includes a first facing layer along a first face thereof. In still another embodiment, the liner/insulator includes a second facing along a second face thereof. The first and second facings may be constructed from polyester, rayon, metallic foil and any mixtures thereof.
In accordance with another aspect of the present invention, an acoustical liner with integral water barrier is provided. The acoustical liner comprises a pad of fibrous material having a lofty, acoustically insulating portion having a density of between substantially 8.0-80.0 kg/m3 and a relatively higher density, water-barrier skin along at least one face thereof. The skin has a thickness of between substantially 0.254-7.5 mm and a density between approximately 32.0-1600.0 kg/m3. The pad is formed from fibrous materials selected from a group consisting of polyester, polyethylene, polypropylene, polyethylene terephthalate, glass fibers, natural fibers and any mixtures thereof. The pad and heat-seared, water-barrier skin are integral and, accordingly, the acoustical liner is a non-laminate. As such, it avoids any tendency to delaminate as is characteristic of the water barrier layers laminated to acoustical insulation materials commonly employed in the prior art.
The acoustical liner with integral water barrier may further include a crimped margin around at least a portion of the periphery of the pad where the crimped margin has a thickness of at least about 0.5-3.0 mm. This margin provides additional strength and a suitable location to mount the liner to, for example, a door panel or other structural component of a vehicle requiring acoustical insulation by means of mechanical fasteners of a nature known in the art.
Of course, the pad of the acoustical liner with integral water barrier may also include two heat-seared skins. Additionally, the pad may include one or more facing layers composed of polyester, rayon, metallic foil and any mixtures thereof.
In accordance with yet another aspect of the present invention a method of insulating a door including an exterior body panel and an interior fascia panel defining a cavity therebetween is provided. The method comprises the placing of a pad of fibrous material in the cavity between the exterior body panel and the interior fascia panel. The pad has a lofty, acoustically insulating portion having a density of substantially 8.0-80.0 kg/m3 and a relatively higher density skin along at least one face thereof having a density of between substantially 0.25-7.5 mm.
In accordance with yet another aspect of the present invention a door for a vehicle is provided. The door includes an exterior body panel, an interior fascia panel connected to the exterior body panel and defining a cavity therebetween and a pad of fibrous material having a lofty, acoustically insulating portion having a density of substantially 8.0-80.0 kg/m3 and a relatively higher density, water-barrier skin along at least one face thereof. That skin has a thickness of between substantially 0.25-7.5 mm. That pad is formed from fibrous materials selected from a group consisting of polyester, polyethylene, polypropylene, polyethylene terephthalate, glass fibers, natural fibers and any mixtures thereof. The pad is a nonlaminate and may also include a crimped margin around at least a portion of the periphery of the pad where the crimped margin has a thickness of at least about 0.5-3.0 mm. As noted above, this crimped margin provides a convenient fastening point for securing the acoustical liner to the exterior and/or interior panels of the door or other component to which the acoustical liner is to be secured. The pad of the acoustical liner may also include two heat-seared skins.
In accordance with still another aspect of the present invention, a liner for an airstream conduit, such as a heating and air conditioning duct, or a housing such as for a furnace or air conditioning unit, is provided. That liner comprises a pad of fibrous material having a lofty, acoustically insulating portion having a density of between about 8.0-80.0 kg/m3. That liner also includes a relatively higher density skin along at least one face thereof. The skin has a thickness of between about 0.25-10.00 mm and a density of between about 32.0-1600.0 kg/m3. The liner may be formed from polyester, polyethylene, polypropylene, polyethylene terephthalate, glass fibers, natural fibers and any mixtures thereof. The liner may also include a second skin and, if desired for any particular application, one or more facings. The facings may be constructed from polyester, rayon, metallic foil and any mixtures thereof.
Still other objects of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described preferred embodiments of this invention, simply by way of illustration of several of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.